Air speed indicator



N vyls, 1946. TT R 2,411,484

AIR SPEED INDICATOR Filed June 9, 1944 2 Sheets-Sheet 1 Nov. 19, 1946.

M. WATTER AIR SPEED INDICATOR 2 Sheets-Sheet 2 Filed June 9-, 1944 INVHVTOR Michael Wane);

ATTORNEY changes to furnish accurate indications. Other 40 wardly toward the front end, here about-9, relais tobe noted that there is a static tube head 12 It is thus seen that the invention provides ac- Patented Nay. 19, 1946 r 2,411,484

[TED STATES PATENT OFFEQE 2,411,484 AIR SPEED INDICATOR Michael Watter, Philadelphia, Pa., asslgnor to The Budd Company, Philadelphia, Pa., a corporation oi Pennsylvania Application June 9, 1944, Serial No. 539,437 3' Claims. (Cl. 73-182) 2 r This invention relates to airspeed indicators, leads to the airspeed indicator instrument I 6 in as for use on aircraft and the like, and has for an the pilot's compartment, thus canceling the efobject the provision of improvements in this art. fects of-cross currents and turns. The dynamic One of the particular objects is to provide an head ll isconnected to the instrument by' a air speed indicator which does not impose paratube ll.

sitic drag on the vehicle on which it is mounted. As shown in Fig. 2, the dynamic head. II is Another object is to provide ready access to all located in a recess It! in the nose and is removaparts of the apparatus at all times. bly secured therein as by screws or bolts l9 in Anothenobiect is to cancel out the effects of the base. A heating coil 20, interior or exterior side currents and turns. 10 of the external tube, is provided to prevent icing Other objects and advantages will be apparent over. A drain 2| m'ay be provided for removing from the following description of illustrative water, if needed, embodiments thereof, reference being made to. I As shown in Fig. 3, the static head [2 is formed the accompanying drawings, wherein: as a hole in a reinforced patch 22 on the nose Fig. 1 is a perspective view of an airplane skin sheet, together with a, mating apertured equipped with this airspeed indicator; nipple fitting plate 23 secured thereto. Pipe Fig. 2 is an enlarged section through the dyfittings, including a union, and a removable box ami h ad or Pitot tube; cover 24 provide access to the outer aperture in Fig. 3 is an enlarged section through the static the skin for cleaning when necessary. Heating head; means 25 located adjacent the outer skin serves Fig. 4 is a perspective view of a modification; to prevent ice forming over the aperture, though d at this location the danger of icing is much less Fig. 5 is a horizontal section. through the body than at the nose. nose of Fig. 4 showing dual instrument tubes. As shown in Figs. 4 and 5. the Pitot tubes ll Referring to the drawings, the vehicle here 25 for registering dynamic pressure may extend a shown is an airplane A, including fuselage B; short distance beyond the nose instead of being wings C, empennage D, and outboard motors E recessed into the nose as in Fig. 2. Two such a, dynami Pit t t be h it igplaced i the pilot. Also the static tube heads M are located of the Pitot tube and the air flowing away from man tube or manifold Ida which connects by the tube head in all directions. Heretofore, it tubes 15' with the instruments it. Thus while has been proposed to place a dynamic tube head the dynamic heads serve each instrument sepain the leading edge of the wings or other susrately, the static heads serve both instruments tentation airfoil but the narrow edge is ailected in common.

too much by shifting currents and climb angle The axis of the dynamic tube is inclineddowninstallations have placed the dynamic and static tive to the fuselage axis. tube heads on a pedestal or outboard projection The bulbous front end of the fuselage is so on either the body or sustentation airfoils but deep vertically and so wide horizontally that the this imposed undesired parasitic drag on the mid-portion is substantially unaffected by air disairplane. turbances, hence the mid-portion of' the front The static tube head i2 is placed on the side end of the fuselage provides a good location for of the body in a position where the airflow is the dynamic head of the air speed indicator, as

dynamic pressure or eddy currents. In Fig. 1 it of a wing which is relatively thin vertically and is placed on the rounded side of the nose, the where changes in the angle of attack greatly optimum point being determined by wind tunnel change the air conditions for a static head which tests or experiment for each particular craft. It may be there located.

on each side of the body and that both a're concurate and accessible means for registering the use by tubes it to a common tube idwhioh airspeed; also that the minimum parasitic drag is im osed: and further that the eilects of side currents and turns are eliminate While certain embodiments of the invention have been described, it is to be understood that there may be various embodiments within the limits of the prior art and the scope of the subjoined claims.

What is claimed is: 3

1. In an airplane having a fuselage which at the front end is so deep vertically as to be substantially unaffected by air disturbances such as those which affect the leading edge of a wing withchanges in the angle of attack, and which front end is disposed clear 01' the propeller stream, the combination therewith of a dynamic head located near the mid-height of the front end of the fuselage, a static head located in each side. of the fuselage, a pressure differential indicating instrument located in said fuselage, and means for conveying effects of air pressure from said dynamic and static heads to said instrument.

2. In an airplane having a fuselage which at the front end is so -deep vertically as to be substantially unaffected by air disturbances such as those which affect the leading edge of a wing with changes in the angle of attack, and which front end is disposed clear of the propeller stream,

' for conveying effects of I dynamic and static the frontend is so deep those which affect the i 4 the combination therewith of a dynamic head located near the mid-height 0f the front end of the fuselage, a static head located in each side of the fuselage, a pressure differential indicating instrument located in said fuselage, and means air pressure from said heads torsaid instrument, all of said heads being attached to the shell of the fuselageiand being removable toward the inside of the shell. l

3. In an .airplane having a fuselage which at vertically as to be subair disturbances such as leading edge of a win with changes in the angleof attack, and which front end is disposed clear of the propeller stream, the combination therewith of a dynamic head located near the mid-height of the front end of the fuselage, a static head located in each side of the fuselage, a pressure differential indicating instantiallyunafiected by strument located in said fuselage, and means for conveying effects of air pressure from said dynamic and static heads face of the shell of said fuselage.

MICHAEL WA'I'IER.

to said instrument, said heads being located wholly within the airfoil sur- 

